The NCAR High Altitude Observatory, The University of Hawaii, and the University of Michigan, propose to build a COronal Solar Magnetism Observatory (COSMO) facility for use by the solar physics research community. The facility will take continuous daytime synoptic measurements of magnetic fields in the solar corona and chromosphere, in order to understand solar eruptive events that drive space weather, and to investigate long-term phenomena. The primary instrument is a 1.5-meter coronagraph with two detector systems, a narrow-band filter polarimeter and a spectropolarimeter. Supporting instruments are a white-light K-coronagraph, and a chromosphere and prominence magnetometer.

New prototype instrumentation developed at the University of Hawaii and at HAO/NCAR have demonstrated that measurements of coronal magnetic fields are now possible. New scientific discoveries have already resulted from these breakthroughs, and a facility that includes a large-aperture solar telescope is a compelling next step to advance research into the solar corona. The observational program emphasizes scientific community involvement, including an open data policy, student participation, and public access to scientific results.